Motor-control system.



J. 0. SMITH. MOTOR CONTROL SYSTEM. APPLICATION IILBD JULY 31, 1911.

1,048,432. Patented De0.24,1912.

WITNES 15s.- 506 '1 ENTOR.

' I ATTORNEY.

JOHN- G. smr'rfi, or LOUISVILLE, KENTUCKY.

P 'ilto'Toa-coNTnoL SYSTEM.

Specification of Letters Patent. 1

permeate... 24,1912.

Application filed July 31, 1911. Serial No. 641,590.

To all whomc't may concern:

Be it known that I, JOHN 0. SMITH, a

citizen of the United States, and residing at Louisville, in the county of Jefferson and State of Kent-ucky,-have invented new and useful Improvements in Motor-Control Systems, of whichthe following is a specification.

This invention relates to the controlling of electric motors, and one ofthe objects is the provision of eflicient means for securing a dynamic braking of the motor.

When current is cut ofi' from the motor there is an induced current through the armature, in the opposite direction to the line current, if the field magnets are excited this will exert a retarding effect on the motor. This invention contemplates taking full advantage of the induced current in the armature by having the field magnets constantly excited. Iaccomplish this by having theshunt-field winding of the motor constantly connected to the line, or source of current supply.

After current is cut off from the motor the'momentum of the load will drive the armature as a generator, the armature turning freely if the circuit is open, but if the armature is short circuited the retarding, or braking effect, will be so great as to bring the motor to a sudden stop. To regulate the braking eifectresistances of the proper ohm'age may be inserted in the circuit across the armature terminals.

With the foregoing and other objects in view, this invention consists of the novel construction of apparatus, and arrangement of circuits to be hereinafter referred to, and

illustrated in the accompanying drawing,

which forms a part of this specification, in which is set forth an embodiment of the in- ?vention, but' it is to be understood that changes, variations and modifications may be resorted to that come within the scope of the claims appended hereunto.

The drawing is a diagrammatic view, or wiring plan, of the invention as applied to a motor for operating an elevator, showing in full lines the position in which the switches stand when the elevator is at rest, and in dotted lines the position assumed when the elevator is going down. The

circuits shown are illustrated and described in my copending application No. 636,825, filed July 5, 1911.

Referring to the drawing I indicates a compound-wound motor, the shunt-field winding of which is connected direct to the line, or source of current supply. The ci'rcuit being from the wall switch H by conductors 2 and 3. to the post F on the switch F, through the lever F to post F, by conductor 4 to contact post E on the switch E, through resistance E to post E to post E, through the magnet coil to binding post E thence by conductorv 5 to motor terminal f, through the shunt-field winding (30 of the motor to terminal f", thence by conduct-or 6 to the wallswitch H. It will be. seen'that line current is supplied to the shunt-field and no provision is made to open, or short circuit it.

Provision is made to short circuit the re sist-ance E as follows; from the binding post E a conductor 19 leads to a contact 113 on the main switch A, andfrom contact 114 conductor 20 leads to the binding post E. As the main switch A closes a contact piece 109 bridges the contacts 113-114,

this short circuits the magnet coil of switch E, the lever E drops and closes contact on the post E the current will then flow through the lever E will receive full line current; this happens before the main switch. closes so that the shunt-field is fully excited when current is given to the armature. The field magnet being excited when current is given to the armature, the motor speeds up quicker than if the lag in the field had first to be overcome. A dynamic braking circuit across the armature terminals, may be traced from the terminal a", by post C on the switch C, through the lever C to post (3, by conductor 43 to and through resistance 44, thence by conductors 45 and 29 to terminal a. This circuit is opened and closed by the switch C, the circuit operating the switch 0 may be traced from the wall switch H by conductors 2 and 38 to binding post 0, by conductors 39 and 41 to contact post 232, through switch lever. 229," when in position, to post 230, thence by conductors l8 and 2 to the wall switch H. From the foregoing it will be seen that the switch C is energized by the ingi thev dynamic braking circuit. The dyconductors 30 and 42 to.

and the shunt-field 45 carried on the elevator car and the lever N? is shifted by stationary guides on the elenamic braking circuit is not opened until the accelerating switch B starts to operate, this is an advantage in starting with a load that would drive the armature, before it receives sufiicient current to overcome the torque caused by the load.

It will be observed that there are two resistance coils in the shunt-field circuit, E regulating the amount of current necessary to secure the proper braking effect, as described, and F to weaken the field for speeding up the motor, after the method well known in the art. The two coils are necessary because the amount of resistance required varies in each case. The resistance E is cut in, and out, of circuit by the switch E as previously described, the resistance F" is cut in, and out, by the switch F, the circuit operating which is adapted to be closed by a manually operated switch K in the elevator car, the closing of the circuit being controlled. by the accelerating switch B through. medium of :the switch lever234, the

object being to prevent the operation of switch F until the accelerating switch has completed its cycle of operations. A slow down switch N is included in the circuit from the switch K, that operates the switch F. Two conductors lead from the car switch K to the slow down switch, one from each side of the switch K. Conductor 49 leading from contact 427 on the upside to contact N this being the circuit when the car is going up. Conductor 57 leading from contact 431 to contact N this being the circuit when the car is going down. From the slow down switch a conductor 50 leads to the speeding up switch F. It will be observed that the shifting of the arm N will open one of the circuits from the car switch to the speeding switch at N or N, and that the speeding switch cannot'again be operated, on that circuit until the lever N is restored, although it may be operated over the other circuit. The slow down s witch is vator supports, as described in my co ending application No. 641,591, filed J y 31, 1911.

The direction in which the armature rotates is governed by the direction of the- [that shown, and described' in my copending fapplication No. 636,825 filed July 5, 1911.

The manually operated switch may be of any desired construction, in which a contactor is adapted to be brought into contact with a series of contacts, when shifted in either direction from a normal position of rest. Referring to the drawing, current is given to the switch K from the wall switch H by conductors 2 and 7, slack cable switch L and conductor 8. Moving the switch K to the right (the down direction) will bring the elevation 422 into contact with the contact finger 428, giving current to the reversing switch, the circuit to, and through, the down solenoid 302, thence by conductor 53 to contact finger 514 on auto limit switch J,

from contact finger 513 thereon by convation 420 into'contact with contact tiger 423, this will give current to the main switch A, the circuit being to, and through the auto-limit switch J thence by conductor 54 to the lower limit switch. Pthence to, and through,a locking coil on the solenoid 302, thence to contact 335, through pilot-.

switch lever 332, thence to, and through, the coil 101 of the main switch A, thence to,

and through pilot-switch lever 229, by con-' ductors 18 and 2-- to wall switch H. This closes the main switch A, the parts assuming the position shown in dotted lines. As

the main switch closes the cont-actor 109 bridges contacts 113114 closing the-shunt around the switch E, as previously explained. Further movement of the switch.

K will bring elevation" 424 into contact with contact finger 429, this will give current tov bringing it into contact with post 232, closing the circuit through switch C, as previously described. The accelerating switch also shifts the pilot lever 238, giving current to one side of switch F by conductors 51 and 35 to the main switch A, current being {given to the other side ofswitch F by a rther movement of the switch K bringing the elevation 422 into contact with the contact finger 431, the circuit being from contact 431 by conductor 57 to contact N on the slow-down switch N, through the lever N?, t ence by conductor 50 to the switch F.

Current is given to the main switch A from the wall switch H by conductor 2 to contact 111, and through lever 123 to points 125 and 133; and from points 126 and 134 through lever 124 to contact 119, thence by conductor 2 to the wall switch H. With the closing of the mainvswitch current is given. tothe brake magnet M as follows, rom point 133, on the main switch, by conductor 21, switch lever D conductor 22 to and through the brake magnet, thence by conductors 23, 18 and 2- to wall switch H. The shifting of the pilot switch lever 229, by the accelerating switch member 212, closes, a circuit from the wall switch H by conductors 2 and 38 to, and through, the coll of switch D, thence by conductors 40 and 41, lever 229, conductors 18 and 2 to thewall switch H; this energizes .the switch D causing it to attract the lever D cutting the resistance D into the brake-magnet circuit, protecting it from over load. With the closing of the main switch current is given to .theseries fieldg and, armature of the motor as follows, from point 125, on the 'main switch, by conductors 24 and 25 to and through the resistance coils 25-'25 and 25", thence by "conductors 26 and 27 to motor terminals 0", through series field 61 to terminal 0, by conductor 28 to 313 on reversing switch G through 317, by conductor 30 to motor terminal a, through armature 62 to terminal a, thence by conductor 29 to and through 317-318 to 316 on reversingswitch G, thence by conductor 31 to 126 on the main switch A; this starts the motor at-slow speed.

The accelerating switch B may be of any suitable construct1on,.inwhich a plurality of members are adapted to operate se'Mati m. to cut resistances in and out of circuit, the first and last members being adapted to shift pilot-switch levers. Members 212213 and 214, of the accelerating sw'itch B contact with the points 224-225 and 2 26 successively cutting the resistances 2525- and 25 out .of the series field and armature circuit; member 215 contacts with point 227 cutting out the series field entirely, the armature circuit then being from 125 on the main switch A by conductor 24 to and through the accelerating switch to point 227 thence by conductors 48 and 28 to 315 on the reversing switch G, through 317 thence b conductor 30 to motor terminal a", throng armature 62 to terminal 0., thence by conductor 29 to the reversing switch G, thence by conductor 31 to point- 126 on the main switch The motor will now be running at about half speed. As the first member 212 of the accelerating switch moves it shifts the pilot-switch lever 229, breaking contact at 231 and making it at 232, opening the operating circuit of the main switch, previously described, at 231' would allow the main switch to drop out, but that the main switch had closed a secondary or holding circuit from contact 231 through resistance 37 to point 134. As thelast member 215 of the accelerating switch moves it 'shifts the pilot-switch lever 238, breaking contact at 236, and making'it at 237. Breaking contact at 236 cuts resistance 234 into the circuit of the solenoid, 201, that operates the accelerating switch, protecting it from overloads. Closing the contact-at 237 gives current to one side of the speeding up switch F by conductor 51. The speeding-up switch may now be energized by the movement of the manual switch K, as previously explained, energization of the switch F causes it toattract lever F 2 cutting resistance F into the shunt fieldcircuit weakening it and speeding the motor. up. The auto-limit switch J belongs toaa class, well known in the art and needing no extended description, that is located on, or in proximity to the motor and is adapted to be connected t ierewith and driven thereby in such relation to the travel of the elevator car, that contactors, included in various of the operating circuits, and bearing on contact segments carried by the switch will run ofi the ends of the segments in predetermined sequence opening the circuits therethrough.

and stopping the car atthe upper and lower landings. independent ofthe operator.

0 and P indicate respectively, upper and lower limit switches included in the circuits from the manual switch K that lead through the locking coils of the reversing switch to the operating solenoid of the main switch A.

L indicates a-- slack cable switch included in the circuit from the'walP- switch to the manual switch. I

M 'ndicates the brake magnet.

These safety devices being well known in the art need no extended description, as any construction may be used, they forming no element of this invention.

Having described my invention so that any one skilled in the art pertaining thereto may make and use the same, I claim 1. In a motor control system, the combination with an electric motor, of a circuit including the shunt field winding thereof, a

plurality of resistances, the source of current supply, a second circuit including the armature and series -field' windings, a switch for closing said second circuit, means controlled by said switch for short circuit Y ing one of said resistances, and means manual y controlled for short circuitin gthe other of said resistances. 2. In a motor control system, the combination with an electric motor, of a'permanently closed circuit including the shunt field and aplurality of resistances, a second circuit including the armature and series field and a, plurality of resistances, a switch for closing said second circuit, a switch for short circuiting the resistance in saidsecond I circuit, means operable by the first mentioned switch for short circuiting one of the first cuiting another of said first mentioned re-- mentioned resistances, and I means controlled by said second switch for short cirbination with an electric motor, of a main switch, an accelerating switch, a braking c1rcu1t across the armature terminals of the motor, a permanently closed circuit including the shunt field and a plurality of resistances, means operable by the closing of the main switch to short circuit one of said resistances, means operable by the action of the accelerating switch to control said braking circuit, and other means operable by the action of the acceleratin switch to control the short circuiting 0 another of said resistances. t Y

5. In motor control apparatus, the combination with an electric motor, of a main switch, an accelerating switch comprising a plurality of members operating serz'atim, a braking circuit across the armature ter-' minals, a permanently closed circuit in cluding the shunt field and a plurality of resistances, means operable by the closing of the main switch to short circuit one of said; resistances, means operable by the first of said accelerating switch members to control the brake circuit, and means operable by the last of said members to control another of said resistances.

' 6..In a motor control system, the combination with an electric motor, of a main sw tch, a permanently closed circuit including the shunt afield, a resistance and an electric switch, said switch adapted when de- 'energized to. short circuit said resistance, I

and means operable by the main switch to denergize said switch.

7. In a motor control apparatus, the combination with an electric motor, of a main switch, an accelerating switch, a braking circuit across the armature terminals, an electric switch adapted to open said circuit, means operable by the accelerating switch to energize said electric switch, a permanently closed circuit including the shunt field, a resistance, and an-electric switch adapted to short circuit said resistance, and means operable by the main switch to deenergize said electric switch.

8. In a s stem of motor control, the combination with an electric motor, of'a main switch, a permanently closed circuit including the shunt field, a resistance and the c011 of an electro-magnetic switch, said switchadapted when deenergized to short circuit said resistance, an open shunt around said coil, and means for closing said shunt thereby short circuiting said coil and deenerg zing the switch. I v

9. In amotor control system, the combination with an electric motor, of permanently closed circuit including 1 the shunt field winding, a resistance, and the coil of an electro-magnetic switch, an open shunt around said coil, a second circuit including the armature and source" of current supply, a'switch for closing s 'd second circuit, and means controlled b said switch for closing said shunt thereby 'short circuiting said'coil and deenergizing said electromagnetic switch.

10. 'In a system of motor control, a motor, the shunt field winding thereof, a resistance and the coil of an electro-ma'gnetic switch being connectedin series, an open shunt around said resistance, an open shunt around the coil, said switch adapted to close the shunt around the resistance, and means for closing the shunt around the coil thereby dee'nergizing said switch.

JOHN 0. SMITH.

I Witnesses:

'W. B. MUNNELL, I

WM. J. SAUER. 

